{{Citation needed}} (also known by the redirects {{Cn}} and {{Fact}}) is a template used to identify questionable claims that lack a citation to a reliable source. It produces a superscripted notation like the following:

Usage

If you don't add a date parameter, a bot will date your entry with the month and year at a later time.

The date parameter consists of the name of the current month and the year only, not full dates. The names of the months are capitalised in English. Any deviation from these two rules will result in an "invalid date parameter" error.

It is also recommended to add the (non-displayed) |reason= parameter to leave a better record for future editors. For example, the following usage might be appropriate to the claim that "Humphrey Bogart has won several snooker world championships.":

{{Citation needed|reason=please give a reliable source for this assertion. I thought he was an actor.}}

When not to use this template

Unsourced or poorly sourced contentious material about living persons should be removed immediately. Do not tag it: immediately remove it. For more information, see the section on poorly sourced contentious material in the Biography of Living Persons policy.

Material that is doubtful and harmful may be removed immediately, rather than tagged. See Burden of evidence. Claims that you think are wrong may alternatively be tagged with {{dubious}}.

If you have the time and ability to find an authoritative reference, please do so. Then add the citation yourself, or correct the article text. After all, the ultimate goal is not to merely identify problems, but to fix them.

Any editor may add this template to any uncited passage for any reason, but many editors object to what they perceive as overuse of this tag, particularly in what is known as "drive-by" tagging, which is applying the tag without attempting to address the issues at all. Consider whether adding this tag in an article is the best approach before using it, and use it judiciously. Wikipedia's verifiability policy does not require reliable sources for common facts (e.g., "The Moon orbits the Earth"), or that citations be repeated through every sentence in a paragraph. All direct quotations and facts whose accuracy might be challenged (e.g., statistics) require citations.

This template is intended for specific passages that need citation. For entire articles or sections that contain significant material lacking sources (rather than just specific short passages), there are other, more appropriate templates, such as {{Unreferenced}} or {{Refimprove}}.

How to respond to this tag

The addition of this tag is a request for an inline citation to support the tagged statement. If you are able to provide a citation to support the claim, then please do so.

Except for certain kinds of claims about living people, which require immediate production of inline citations, there is no specific deadline for providing citations. Please do not delete information that you believe is correct simply because no editor has bothered to provide a citation within an arbitrary time limit. Where there is some uncertainty about its accuracy, most editors are willing to wait about a month to see whether a citation can be provided.